This is Hudavent Hatun Turbesi.

The Anatolian Seljuk ruler IV. The Sword of Rukneddin was made by Hudavend Hatun, daughter of Lion. The mausoleum, which has undergone some repairs to date, retains its original character. The structure belongs to a group of single-storey and octagonal shrines. In the construction of the structure, yellowish-colored fine-grained trachyte stone was used; white marble was used in the doors and windows, arches and lintels, as well as in the belts and booklets in the cabinet. The decorations on the pointed arches of the vault, the figurative decorations on the windows and the reddish-brown stone, which is finer textured and harder in the window grilles; the black cut stone is used in the deaf pointed arches of the dome of the interior.